Table.1. Molecular properties of senescence barriers encountered by cultured HMEC
SENESCENCE |
Morphology |
SA-β-Gal |
p16 |
p53 |
Arrest |
LI(%) |
Karyotype |
Mean |
53BP1 |
ser15P |
STASIS |
senescent# |
+ |
+ |
IND |
viable in G1 |
<2 |
normal |
~6-9kb |
+ |
-/+ |
Replicative Senescence: |
senescent |
+ |
- |
+ |
mostly viable all phases, some death |
~15 |
abnormal |
~4-5kb |
+++ |
++ |
Replicative Senescence: |
growing, |
+ |
- |
- |
eventual massive death |
~40 |
abnormal |
<5kb |
ND |
ND |
OIS |
sick, dying, |
-/?* |
IND |
IND |
all phases |
~15 |
IND |
IND |
ND |
ND |
Isogenic |
senescent |
+ |
+ |
IND |
viable in G1 |
<2 |
normal |
~6kb |
+ |
- |
IND: senescence barrier independent of that property; ND: not determined
#: HMEC arrested at stasis in MCDB 170 have a morphology showing abundant stress fibers
*: negative in pre-stasis HMEC; could not be determined in post-selection HMEC.
The expression of 53BP1 foci and serine 15 phosphorylated p53 are markers of a DDR.